Human skin color | EPFL Graph Search

Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among individuals is caused by variation in pigmentation, which is the result of genetics (inherited from one's biological parents and or individual gene alleles), exposure to the sun, natural and sexual selection, or all of these. Differences across populations evolved through natural selection or sexual selection, because of social norms and differences in environment, as well as regulations of the biochemical effects of ultraviolet radiation penetrating the skin. The actual skin color of different humans is affected by many substances, although the single most important substance is the pigment melanin. Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin color of darker-skin humans. The skin color of people with light skin is determined mainly by the bluish-white connective tissue under the dermis and by the hemoglobin circulating in the veins of the dermis. The red color underlying the skin becomes more visible, especially in the face, when, as consequence of physical exercise or sexual arousal, or the stimulation of the nervous system (anger, embarrassment), arterioles dilate. Color is not entirely uniform across an individual's skin; for example, the skin of the palm and the sole is lighter than most other skin, and this is especially noticeable in darker-skinned people. There is a direct correlation between the geographic distribution of ultraviolet radiation (UVR) and the distribution of indigenous skin pigmentation around the world. Areas that receive higher amounts of UVR, generally located closer to the equator, tend to have darker-skinned populations. Areas that are far from the tropics and closer to the poles have lower intensity of UVR, which is reflected in lighter-skinned populations. Some researchers suggest that human populations over the past 50,000 years have changed from dark-skinned to light-skinned and vice versa as they migrated to different UV zones, and that such major changes in pigmentation may have happened in as little as 100 generations (≈2,500 years) through selective sweeps.

Thermal sensing device and sensory feedback system and method using such thermal sensing device

Silvestro Micera, Solaiman Shokur, Outman Akouissi, Jonathan Louis Muheim, Francesco Iberite

The present invention concerns a thermal sensing device (1) and a sensory feedback system and method using such thermal sensing device, comprising at least one film (19) of electrically insulating polymer defining a global surface of the thermal sensing de ...

2024

First Advanced Bilayer Scaffolds for Tailored Skin Tissue Engineering Produced via Electrospinning and Melt Electrowriting

Biranche Tandon, Nicolas Tissot

In vitro skin models are validated methods for screening cosmetics and pharmaceuticals, but still have limitations. The bilayer poly(epsilon-caprolactone) scaffold/membrane model described here overcomes some of these deficits by integrating a solution ele ...

Weinheim2024

Morphological and Material Programability of a Hall-Effect Based Soft Tactile Sensors

Josephine Anna Eleanor Hughes, Sudong Lee

The different receptors in human skin show not only diversity in the stimuli to which they respond, but also variable sensitivity and directionality. This is often determined by their location or morphology, and can play an important role in filtering or a ...

IEEE2024